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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #411501
Research Project: Adaptive Grazing Management and Decision Support to Enhance Ecosystem Services in the Western Great Plains

Location: Rangeland Resources & Systems Research

Title: Disturbances in drylands: Interactions among herbivory, drought, and termite activity in savanna communities

Author
item WELLS, HARRY - Princeton University
item KIMUYU, DUNCAN - Karatina University
item ODADI, WILFRED - Egerton University
item CHARLES, GRACE - Mpala Research Centre And Wildlife Foundation
item VEBLEN, KARI - Utah State University
item Porensky, Lauren
item REGINOS, CORINNA - The Nature Conservancy
item EBEL, CARMEN - University Of Oregon
item EKADELI, JACKSON - Mpala Research Centre And Wildlife Foundation
item NAMORI, MATHEW - Mpala Research Centre And Wildlife Foundation

Submitted to: Journal of Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Disturbance is in important part of how ecosystems work. But, the combined effects of different types of disturbance are not well understood. Climate change is predicted to cause more frequent and intense extreme weather events, such as droughts, but how the effects of these events will depend on other types of disturbance is unclear. For example, the effects of droughts on plants may depend on the presence of large herbivorous mammals and ecosystem-engineering insects like termites. We use a long-term 28-year controlled experiment in an African savanna to show that the effects of these three forms of disturbance (drought, herbivores, and termites) do indeed interact, resulting in lower vegetation cover than expected based on the combination of each of their effects in isolation. Our study highlights the importance of long-term controlled experiments to understand such complex interactions.

Technical Abstract: Disturbance is crucial to ecosystem dynamics, but combined effects of multiple interacting disturbances are poorly understood. Climate models predict increases in the frequency and intensity of extreme weather, but the impacts of these events may be modulated by biotic disturbance agents in unpredictable ways. We used a 28-year experiment to investigate how droughts, large herbivores, and soil-engineering termites interact to regulate understory vegetation in a semi-arid African savanna. Herbivory was the dominant driver of understory cover and richness, and its interactive effects with drought and termites on cover were non-additive — and thus not predictable from main effects or pairwise interactions. Herbivory favoured the occurrence of annual plants more than perennials, suggesting that plant species’ responses to large-mammal herbivory in other ecosystems are predictable from their life history strategies. Our study underscores the importance of long-term controlled experiments encompassing multiple extreme climate events, which enable such complex interactions to be disentangled.